libhydra: Remove empty unused library

src/charon/Makefile.am

@@ -7,7 +7,6 @@ charon.o :	$(top_builddir)/config.status
 
 AM_CPPFLAGS = \
 	-I$(top_srcdir)/src/libstrongswan \
-	-I$(top_srcdir)/src/libhydra \
 	-I$(top_srcdir)/src/libcharon \
 	-DIPSEC_DIR=\"${ipsecdir}\" \
 	-DIPSEC_PIDDIR=\"${piddir}\" \
@@ -15,7 +14,6 @@ AM_CPPFLAGS = \
 
 charon_LDADD = \
 	$(top_builddir)/src/libstrongswan/libstrongswan.la \
-	$(top_builddir)/src/libhydra/libhydra.la \
 	$(top_builddir)/src/libcharon/libcharon.la \
 	-lm $(PTHREADLIB) $(DLLIB)